[OpenMP][WIP] Add standard notes for ELF offload images

[vzakhari]

Summary

This patch adds standard ELF notes into SHT_NOTE sections of ELF offload images passed to clang-offload-wrapper. The notes then can be read by the offload plugins to get some extra information about the image.

The new notes use a null-terminated "LLVMOMPOFFLOAD" note name. There are currently three types of notes:

• VERSION: a string (not null-terminated) representing the ELF offload image structure. The current version '1.0' does not put any restrictions on the structure of the image. If we ever need to come up with a common structure for ELF offload images (e.g. to be able to analyze the images in libomptarget in some standard way), then we will introduce new versions.
• PRODUCER: a vendor specific name of the producing toolchain. Upstream LLVM uses "LLVM" (not null-terminated).
• PRODUCER_VERSION: a vendor specific version of the producing toolchain. Upstream LLVM uses LLVM_VERSION_STRING with optional <space> LLVM_REVISION.

All three notes are not mandatory currently.

The second part of the patch implements an ELF light interface for the plugins to be able to ierate ELF notes in SHT/PT_NOTE sections/segments. One implementation is based on libelf and it can be used for platforms, where libelf depdency can be easily satisfied. The second implementation is based on LLVM ELFObjectFile and requires in-tree build - this one can be used on Windows, etc.

Debug output from the plugins would look like this:

TARGET Common ELF --> LLVMOMPOFFLOAD ELF note NT_LLVM_OPENMP_OFFLOAD_VERSION with value: '1.0'
TARGET Common ELF --> LLVMOMPOFFLOAD ELF note NT_LLVM_OPENMP_OFFLOAD_PRODUCER with value: 'LLVM'
TARGET Common ELF --> LLVMOMPOFFLOAD ELF note NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION with value: '13.0.0git 9f8975163c75b1f9f736f9a8e0a60e29ac062754'

TODOs:

• Find the right place to document clang-offload-wrapper behavior for ELF images.
• Write LIT tests.
• Decide how to test the LLVM ELF implementation of ELF light, since I expect the upstream builds will use libelf implementation.

[vzakhari]

Fixed issues detected in Windows testing downstream.

[jhenderson]

It might make sense to do the llvm-readobj portions of this patch in a separate review, since they are somewhat independent.

[vzakhari]

In D99360#2652523, @jhenderson wrote:

It might make sense to do the llvm-readobj portions of this patch in a separate review, since they are somewhat independent.

I agree. I actually have them in two patches, but I squashed them together for the complete story. If everyone agrees with this in general, I will upload two separate clang-formatted patches.

[MaskRay]

It might make sense to do the llvm-readobj portions of this patch in a separate review, since they are somewhat independent.

+1. Patches touching BinaryFormat/llvm-readobj/yaml2obj/etc part and others (MC/CodeGen/etc) are often required to do BinaryFormat/llvm-readobj/yaml2obj/etc separately.
The part is usually very loosely connected with the MC/CodeGen/etc part code.

Decide how to test the LLVM ELF implementation of ELF light, since I expect the upstream builds will use libelf implementation.

Does the current code use both llvm/Object and libelf? First, for in-tree components we exclusively use llvm/Object - there should be no dependency on the external libelf.
Having two implementations can make llvm/Object API refactoring difficult. Other contributors will not know that an libelf implementation (a different configuration) exists and can break the libelf implementation.

clang/tools/clang-offload-wrapper/ClangOffloadWrapper.cpp

327

sys::findProgramByName tests the filename with an .exe suffix appended, no need to duplicate it in application code.

openmp/libomptarget/plugins/common/elf_common/elf_light.cpp

48

C++ does not require the use sites to prepend struct so typedef struct is not used by convention.

[vzakhari]

In D99360#2654244, @MaskRay wrote:

It might make sense to do the llvm-readobj portions of this patch in a separate review, since they are somewhat independent.

+1. Patches touching BinaryFormat/llvm-readobj/yaml2obj/etc part and others (MC/CodeGen/etc) are often required to do BinaryFormat/llvm-readobj/yaml2obj/etc separately.
The part is usually very loosely connected with the MC/CodeGen/etc part code.

Thanks. I split the patches.

Decide how to test the LLVM ELF implementation of ELF light, since I expect the upstream builds will use libelf implementation.

Does the current code use both llvm/Object and libelf? First, for in-tree components we exclusively use llvm/Object - there should be no dependency on the external libelf.

The current code uses only libelf. I believe many OpenMP offload plugins have been using libelf for a long time, and they did not switch to LLVM/Object, when libomptarget was merged into the tree. I am not going to change this now, because this may cause too much disturbance downstream. The purpose of this patch is to make some ELF reading functionality available in OSes, where it is (historically) unreasonable to require libelf dependency for user environments.

Having two implementations can make llvm/Object API refactoring difficult. Other contributors will not know that an libelf implementation (a different configuration) exists and can break the libelf implementation.

I think it will be actually vice versa :) the upstream and many downstream repos will continue to use the libelf path, and the LLVM/Object path may be broken, as you say. At the same time, we will have QA testing downstream for the LLVM/Object path, so I will be able to catch issues and upstream the fixes.

clang/tools/clang-offload-wrapper/ClangOffloadWrapper.cpp

327

Thanks! Fixed in D99551.

openmp/libomptarget/plugins/common/elf_common/elf_light.cpp

48

Thanks! Fixed in D99553.

[vzakhari]

The revision was split into: D99612, D99551, D99552, D99553

clang/tools/clang-offload-wrapper/ClangOffloadWrapper.cpp

 /// packaged as data. Wrapper bitcode also includes initialization code which
 /// registers target binaries in offloading runtime at program startup.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "clang/Basic/Version.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Triple.h"
+#include "llvm/BinaryFormat/ELF.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
+#include "llvm/Object/ELFObjectFile.h"
+#include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/EndianStream.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Program.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/ToolOutputFile.h"
+#include "llvm/Support/VCSRevision.h"
 #include "llvm/Support/WithColor.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"
 #include <cassert>
 #include <cstdint>
 
+#define OPENMP_OFFLOAD_IMAGE_VERSION "1.0"
+
 using namespace llvm;
+using namespace llvm::object;
 
 static cl::opt<bool> Help("h", cl::desc("Alias for -help"), cl::Hidden);
 
 // Mark all our options with this category, everything else (except for -version
 // and -help) will be hidden.
 static cl::OptionCategory
     ClangOffloadWrapperCategory("clang-offload-wrapper options");
 
 static cl::opt<std::string> Output("o", cl::Required,
                                    cl::desc("Output filename"),
                                    cl::value_desc("filename"),
                                    cl::cat(ClangOffloadWrapperCategory));
 
 static cl::list<std::string> Inputs(cl::Positional, cl::OneOrMore,
                                     cl::desc("<input files>"),
                                     cl::cat(ClangOffloadWrapperCategory));
 
 static cl::opt<std::string>
     Target("target", cl::Required,
            cl::desc("Target triple for the output module"),
            cl::value_desc("triple"), cl::cat(ClangOffloadWrapperCategory));
 
+static cl::opt<bool> SaveTemps("save-temps",
+    cl::desc("Save temporary files that may be produced by the tool. "
+             "This option forces print-out of the temporary files' names."),
+    cl::Hidden);
+
 namespace {
 
 class BinaryWrapper {
   LLVMContext C;
   Module M;
 
   StructType *EntryTy = nullptr;
   StructType *ImageTy = nullptr;
   StructType *DescTy = nullptr;
 
+  std::string ToolName;
+  std::string ObjcopyPath;
+  // Temporary file names that may be created during adding notes
+  // to ELF offload images. Use -save-temps to keep them and also
+  // see their names. A temporary file's name includes the name
+  // of the original input ELF image, so you can easily match
+  // them, if you have multiple inputs.
+  std::vector<std::string> TempFiles;
+
 private:
   IntegerType *getSizeTTy() {
     switch (M.getDataLayout().getPointerTypeSize(Type::getInt8PtrTy(C))) {
     case 4u:
       return Type::getInt32Ty(C);
     case 8u:
       return Type::getInt64Ty(C);
     }
void createUnregisterFunction(GlobalVariable *BinDesc) {
     Builder.CreateRetVoid();
 
     // Add this function to global destructors.
     // Match priority of __tgt_register_lib
     appendToGlobalDtors(M, Func, /*Priority*/ 1);
   }
 
 public:
-  BinaryWrapper(StringRef Target) : M("offload.wrapper.object", C) {
+  BinaryWrapper(StringRef Target, StringRef ToolName)
+    : M("offload.wrapper.object", C), ToolName(ToolName) {
     M.setTargetTriple(Target);
+    ErrorOr<std::string> ObjcopyPathOrErr =
+        sys::findProgramByName("llvm-objcopy");
+    if (!ObjcopyPathOrErr) {
+#ifdef _WIN32
+      // Look for llvm-objcopy.exe as well.
+      ObjcopyPathOrErr = sys::findProgramByName("llvm-objcopy.exe");
+      if (!ObjcopyPathOrErr) {
+#endif // _WIN32
+        WithColor::warning(errs(), ToolName) <<
+          "cannot find llvm-objcopy[.exe] in PATH; ELF notes cannot be added.\n";
+#ifdef _WIN32
+      }
+#endif // _WIN32
+    }
+
+    if (ObjcopyPathOrErr)
+      ObjcopyPath = *ObjcopyPathOrErr;
+  }
+
+  ~BinaryWrapper() {
+    if (TempFiles.empty())
+      return;
+
+    StringRef ToolNameRef(ToolName);
+    auto warningOS = [ToolNameRef]() -> raw_ostream & {
+      return WithColor::warning(errs(), ToolNameRef);
+    };
+
+    for (auto &F : TempFiles) {
+      if (SaveTemps) {
+        warningOS() << "keeping temporary file " << F << "\n";
+        continue;
+      }
+
+      auto EC = sys::fs::remove(F, false);
+      if (EC)
+        warningOS() << "cannot remove temporary file " << F <<
+            ": " << EC.message().c_str() << "\n";
+    }
   }
 
   const Module &wrapBinaries(ArrayRef<ArrayRef<char>> Binaries) {
     GlobalVariable *Desc = createBinDesc(Binaries);
     assert(Desc && "no binary descriptor");
     createRegisterFunction(Desc);
     createUnregisterFunction(Desc);
     return M;
   }
+
+  std::unique_ptr<MemoryBuffer> addELFNotes(
+      std::unique_ptr<MemoryBuffer> Buf,
+      StringRef OriginalFileName) {
+    // Cannot add notes, if llvm-objcopy is not available.
+    //
+    // I did not find a clean way to add a new notes section into an existing
+    // ELF file. llvm-objcopy seems to recreate a new ELF from scratch,
+    // and we just try to use llvm-objcopy here.
+    if (ObjcopyPath.empty())
+      return std::move(Buf);
+
+    StringRef ToolNameRef(ToolName);
+
+    // Helpers to emit warnings.
+    auto warningOS = [ToolNameRef]() -> raw_ostream & {
+      return WithColor::warning(errs(), ToolNameRef);
+    };
+    auto handleErrorAsWarning = [ToolNameRef, &warningOS](Error E) {
+      logAllUnhandledErrors(std::move(E), warningOS());
+    };
+
+    Expected<std::unique_ptr<ObjectFile>> BinOrErr =
+        ObjectFile::createELFObjectFile(Buf->getMemBufferRef(),
+                                        /*InitContent=*/false);
+    if (Error E = BinOrErr.takeError()) {
+      consumeError(std::move(E));
+      // This warning is questionable, but let it be here,
+      // assuming that most OpenMP offload models use ELF offload images.
+      warningOS() << OriginalFileName <<
+          " is not an ELF image, so notes cannot be added to it.\n";
+      return std::move(Buf);
+    }
+
+    // If we fail to add the note section, we just pass through the original
+    // ELF image for wrapping. At some point we should enforce the note section
+    // and start emitting errors vs warnings.
+    support::endianness Endianness;
+    if (isa<ELF64LEObjectFile>(BinOrErr->get()) ||
+        isa<ELF32LEObjectFile>(BinOrErr->get())) {
+      Endianness = support::little;
+    } else if (isa<ELF64BEObjectFile>(BinOrErr->get()) ||
+               isa<ELF32BEObjectFile>(BinOrErr->get())) {
+      Endianness = support::big;
+    } else {
+      warningOS() << OriginalFileName <<
+          " is an ELF image of unrecognized format.\n";
+      return std::move(Buf);
+    }
+
+    // Create temporary file for the data of a new SHT_NOTE section.
+    // We fill it in with data and then pass to llvm-objcopy invocation
+    // for reading.
+    Twine NotesFileModel = OriginalFileName + Twine(".elfnotes.%%%%%%%.tmp");
+    Expected<sys::fs::TempFile> NotesTemp =
+        sys::fs::TempFile::create(NotesFileModel);
+    if (Error E = NotesTemp.takeError()) {
+      handleErrorAsWarning(createFileError(NotesFileModel, std::move(E)));
+      return std::move(Buf);
+    }
+    TempFiles.push_back(NotesTemp->TmpName);
+
+    // Create temporary file for the updated ELF image.
+    // This is an empty file that we pass to llvm-objcopy invocation
+    // for writing.
+    Twine ELFFileModel = OriginalFileName + Twine(".elfwithnotes.%%%%%%%.tmp");
+    Expected<sys::fs::TempFile> ELFTemp =
+        sys::fs::TempFile::create(ELFFileModel);
+    if (Error E = ELFTemp.takeError()) {
+      handleErrorAsWarning(createFileError(ELFFileModel, std::move(E)));
+      return std::move(Buf);
+    }
+    TempFiles.push_back(ELFTemp->TmpName);
+
+    // Keep the new ELF image file to reserve the name for the future
+    // llvm-objcopy invocation.
+    std::string ELFTmpFileName = ELFTemp->TmpName;
+    if (Error E = ELFTemp->keep(ELFTmpFileName)) {
+      handleErrorAsWarning(createFileError(ELFTmpFileName, std::move(E)));
+      return std::move(Buf);
+    }
+
+    // Write notes to the *elfnotes*.tmp file.
+    raw_fd_ostream NotesOS(NotesTemp->FD, false);
+
+    struct NoteTy {
+      // Note name is a null-terminated "LLVMOMPOFFLOAD".
+      std::string Name;
+      // Note type defined in llvm/include/llvm/BinaryFormat/ELF.h.
+      uint32_t Type = 0;
+      // Each note has type-specific associated data.
+      std::string Desc;
+
+      NoteTy(std::string &&Name, uint32_t Type, std::string &&Desc)
+        : Name(std::move(Name)), Type(Type), Desc(std::move(Desc)) {}
+    };
+
+    // So far we emit just three notes.
+    SmallVector<NoteTy, 3> Notes;
+    // Version of the offload image identifying the structure of the ELF image.
+    // Version 1.0 does not have any specific requirements.
+    // We may come up with some structure that has to be honored by all
+    // offload implementations in future (e.g. to let libomptarget
+    // get some information from the offload image).
+    Notes.emplace_back("LLVMOMPOFFLOAD", ELF::NT_LLVM_OPENMP_OFFLOAD_VERSION,
+        OPENMP_OFFLOAD_IMAGE_VERSION);
+    // This is a producer identification string. We are LLVM!
+    Notes.emplace_back("LLVMOMPOFFLOAD", ELF::NT_LLVM_OPENMP_OFFLOAD_PRODUCER,
+        "LLVM");
+    // This is a producer version. Use the same format that is used
+    // by clang to report the LLVM version.
+    Notes.emplace_back("LLVMOMPOFFLOAD",
+        ELF::NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION, LLVM_VERSION_STRING
+#ifdef LLVM_REVISION
+        " " LLVM_REVISION
+#endif
+        );
+
+    // Return the amount of padding required for a blob of N bytes
+    // to be aligned to Alignment bytes.
+    auto getPadAmount = [](uint32_t N, uint32_t Alignment) -> uint32_t {
+      uint32_t Mod = (N % Alignment);
+      if (Mod == 0)
+        return 0;
+      return Alignment - Mod;
+    };
+    auto emitPadding = [&getPadAmount](raw_ostream &OS, uint32_t Size) {
+      for (uint32_t I = 0; I < getPadAmount(Size, 4); ++I)
+        OS << '\0';
+    };
+
+    // Put notes into the file.
+    for (auto &N : Notes) {
+      assert(!N.Name.empty() && "We should not create notes with empty names.");
+      // Name must be null-terminated.
+      if (N.Name.back() != '\0')
+        N.Name += '\0';
+      uint32_t NameSz = N.Name.size();
+      uint32_t DescSz = N.Desc.size();
+      // A note starts with three 4-byte values:
+      //   NameSz
+      //   DescSz
+      //   Type
+      // These three fields are endian-sensitive.
+      support::endian::write<uint32_t>(NotesOS, NameSz, Endianness);
+      support::endian::write<uint32_t>(NotesOS, DescSz, Endianness);
+      support::endian::write<uint32_t>(NotesOS, N.Type, Endianness);
+      // Next, we have a null-terminated Name padded to a 4-byte boundary.
+      NotesOS << N.Name;
+      emitPadding(NotesOS, NameSz);
+      if (DescSz == 0)
+        continue;
+      // Finally, we have a descriptor, which is an arbitrary flow of bytes.
+      NotesOS << N.Desc;
+      emitPadding(NotesOS, DescSz);
+    }
+    NotesOS.flush();
+
+    // Keep the notes file.
+    std::string NotesTmpFileName = NotesTemp->TmpName;
+    if (Error E = NotesTemp->keep(NotesTmpFileName)) {
+      handleErrorAsWarning(createFileError(NotesTmpFileName, std::move(E)));
+      return std::move(Buf);
+    }
+
+    // Run llvm-objcopy like this:
+    //   llvm-objcopy --add-section=.note.openmp=<notes-tmp-file-name> \
+    //       <orig-file-name> <elf-tmp-file-name>
+    //
+    // This will add a SHT_NOTE section on top of the original ELF.
+    std::vector<StringRef> Args;
+    Args.push_back(ObjcopyPath);
+    std::string Option("--add-section=.note.openmp=" + NotesTmpFileName);
+    Args.push_back(Option);
+    Args.push_back(OriginalFileName);
+    Args.push_back(ELFTmpFileName);
+    bool ExecutionFailed = false;
+    std::string ErrMsg;
+    (void)sys::ExecuteAndWait(ObjcopyPath, Args,
+        /*Env=*/llvm::None, /*Redirects=*/{}, /*SecondsToWait=*/0,
+        /*MemoryLimit=*/0, &ErrMsg, &ExecutionFailed);
+
+    if (ExecutionFailed) {
+      warningOS() << ErrMsg << "\n";
+      return std::move(Buf);
+    }
+
+    // Substitute the original ELF with new one.
+    ErrorOr<std::unique_ptr<MemoryBuffer>> BufOrErr =
+        MemoryBuffer::getFile(ELFTmpFileName);
+    if (!BufOrErr) {
+      handleErrorAsWarning(createFileError(ELFTmpFileName,
+                                           BufOrErr.getError()));
+      return std::move(Buf);
+    }
+
+    return std::move(*BufOrErr);
+  }
 };
 
 } // anonymous namespace
 
 int main(int argc, const char **argv) {
   sys::PrintStackTraceOnErrorSignal(argv[0]);
 
   cl::HideUnrelatedOptions(ClangOffloadWrapperCategory);
int main(int argc, const char **argv) {
   };
 
   if (Triple(Target).getArch() == Triple::UnknownArch) {
     reportError(createStringError(
         errc::invalid_argument, "'" + Target + "': unsupported target triple"));
     return 1;
   }
 
+  BinaryWrapper Wrapper(Target, argv[0]);
+
   // Read device binaries.
   SmallVector<std::unique_ptr<MemoryBuffer>, 4u> Buffers;
   SmallVector<ArrayRef<char>, 4u> Images;
   Buffers.reserve(Inputs.size());
   Images.reserve(Inputs.size());
   for (const std::string &File : Inputs) {
     ErrorOr<std::unique_ptr<MemoryBuffer>> BufOrErr =
         MemoryBuffer::getFileOrSTDIN(File);
     if (!BufOrErr) {
       reportError(createFileError(File, BufOrErr.getError()));
       return 1;
     }
+    std::unique_ptr<MemoryBuffer> Buffer(std::move(*BufOrErr));
+    if (File != "-") {
+      // Adding ELF notes for STDIN is not supported yet.
+      Buffer = Wrapper.addELFNotes(std::move(Buffer), File);
+    }
     const std::unique_ptr<MemoryBuffer> &Buf =
-        Buffers.emplace_back(std::move(*BufOrErr));
+        Buffers.emplace_back(std::move(Buffer));
     Images.emplace_back(Buf->getBufferStart(), Buf->getBufferSize());
   }
 
   // Create the output file to write the resulting bitcode to.
   std::error_code EC;
   ToolOutputFile Out(Output, EC, sys::fs::OF_None);
   if (EC) {
     reportError(createFileError(Output, EC));
     return 1;
   }
 
   // Create a wrapper for device binaries and write its bitcode to the file.
-  WriteBitcodeToFile(BinaryWrapper(Target).wrapBinaries(
+  WriteBitcodeToFile(Wrapper.wrapBinaries(
                          makeArrayRef(Images.data(), Images.size())),
                      Out.os());
   if (Out.os().has_error()) {
     reportError(createFileError(Output, Out.os().error()));
     return 1;
   }
 
   // Success.
   Out.keep();
   return 0;
 }

llvm/include/llvm/BinaryFormat/ELF.h

 };
 
 // AMDGPU vendor specific notes. (Code Object V3)
 enum {
   // Note types with values between 0 and 31 (inclusive) are reserved.
   NT_AMDGPU_METADATA = 32
 };
 
+// LLVMOMPOFFLOAD specific notes.
+enum : unsigned {
+  NT_LLVM_OPENMP_OFFLOAD_VERSION = 1,
+  NT_LLVM_OPENMP_OFFLOAD_PRODUCER = 2,
+  NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION = 3
+};
+
 enum {
   GNU_ABI_TAG_LINUX = 0,
   GNU_ABI_TAG_HURD = 1,
   GNU_ABI_TAG_SOLARIS = 2,
   GNU_ABI_TAG_FREEBSD = 3,
   GNU_ABI_TAG_NETBSD = 4,
   GNU_ABI_TAG_SYLLABLE = 5,
   GNU_ABI_TAG_NACL = 6,

llvm/tools/llvm-readobj/ELFDumper.cpp

 static std::string getGNUBuildId(ArrayRef<uint8_t> Desc) {
   std::string str;
   raw_string_ostream OS(str);
   for (uint8_t B : Desc)
     OS << format_hex_no_prefix(B, 2);
   return OS.str();
 }
 
-static StringRef getGNUGoldVersion(ArrayRef<uint8_t> Desc) {
+static StringRef getDescAsStringRef(ArrayRef<uint8_t> Desc) {
   return StringRef(reinterpret_cast<const char *>(Desc.data()), Desc.size());
 }
 
 template <typename ELFT>
 static bool printGNUNote(raw_ostream &OS, uint32_t NoteType,
                          ArrayRef<uint8_t> Desc) {
   // Return true if we were able to pretty-print the note, false otherwise.
   switch (NoteType) {
   default:
     return false;
   case ELF::NT_GNU_ABI_TAG: {
     const GNUAbiTag &AbiTag = getGNUAbiTag<ELFT>(Desc);
     if (!AbiTag.IsValid)
       OS << "    <corrupt GNU_ABI_TAG>";
     else
       OS << "    OS: " << AbiTag.OSName << ", ABI: " << AbiTag.ABI;
     break;
   }
   case ELF::NT_GNU_BUILD_ID: {
     OS << "    Build ID: " << getGNUBuildId(Desc);
     break;
   }
   case ELF::NT_GNU_GOLD_VERSION:
-    OS << "    Version: " << getGNUGoldVersion(Desc);
+    OS << "    Version: " << getDescAsStringRef(Desc);
     break;
   case ELF::NT_GNU_PROPERTY_TYPE_0:
     OS << "    Properties:";
     for (const std::string &Property : getGNUPropertyList<ELFT>(Desc))
       OS << "    " << Property << "\n";
     break;
   }
   OS << '\n';
   return true;
 }
 
+template <typename ELFT>
+static bool printLLVMOMPOFFLOADNote(raw_ostream &OS, uint32_t NoteType,
+                                    ArrayRef<uint8_t> Desc) {
+  switch (NoteType) {
+  default:
+    return false;
+  case ELF::NT_LLVM_OPENMP_OFFLOAD_VERSION:
+    OS << "    Version: " << getDescAsStringRef(Desc);
+    break;
+  case ELF::NT_LLVM_OPENMP_OFFLOAD_PRODUCER:
+    OS << "    Producer: " << getDescAsStringRef(Desc);
+    break;
+  case ELF::NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION:
+    OS << "    Producer version: " << getDescAsStringRef(Desc);
+    break;
+  }
+  OS << '\n';
+  return true;
+}
+
 static const EnumEntry<unsigned> FreeBSDFeatureCtlFlags[] = {
     {"ASLR_DISABLE", NT_FREEBSD_FCTL_ASLR_DISABLE},
     {"PROTMAX_DISABLE", NT_FREEBSD_FCTL_PROTMAX_DISABLE},
     {"STKGAP_DISABLE", NT_FREEBSD_FCTL_STKGAP_DISABLE},
     {"WXNEEDED", NT_FREEBSD_FCTL_WXNEEDED},
     {"LA48", NT_FREEBSD_FCTL_LA48},
     {"ASG_DISABLE", NT_FREEBSD_FCTL_ASG_DISABLE},
 };
static const NoteType AMDNoteTypes[] = {
     {ELF::NT_AMD_HSA_ISA_NAME, "NT_AMD_HSA_ISA_NAME (AMD HSA ISA Name)"},
     {ELF::NT_AMD_PAL_METADATA, "NT_AMD_PAL_METADATA (AMD PAL Metadata)"},
 };
 
 static const NoteType AMDGPUNoteTypes[] = {
     {ELF::NT_AMDGPU_METADATA, "NT_AMDGPU_METADATA (AMDGPU Metadata)"},
 };
 
+static const NoteType LLVMOMPOFFLOADNoteTypes[] = {
+    {ELF::NT_LLVM_OPENMP_OFFLOAD_VERSION,
+     "NT_LLVM_OPENMP_OFFLOAD_VERSION (image format version)"},
+    {ELF::NT_LLVM_OPENMP_OFFLOAD_PRODUCER,
+     "NT_LLVM_OPENMP_OFFLOAD_PRODUCER (producing toolchain)"},
+    {ELF::NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION,
+     "NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION (producing toolchain version)"},
+};
+
 static const NoteType CoreNoteTypes[] = {
     {ELF::NT_PRSTATUS, "NT_PRSTATUS (prstatus structure)"},
     {ELF::NT_FPREGSET, "NT_FPREGSET (floating point registers)"},
     {ELF::NT_PRPSINFO, "NT_PRPSINFO (prpsinfo structure)"},
     {ELF::NT_TASKSTRUCT, "NT_TASKSTRUCT (task structure)"},
     {ELF::NT_AUXV, "NT_AUXV (auxiliary vector)"},
     {ELF::NT_PSTATUS, "NT_PSTATUS (pstatus structure)"},
     {ELF::NT_FPREGS, "NT_FPREGS (floating point registers)"},
if (Name == "FreeBSD") {
     } else {
       return FindNote(FreeBSDNoteTypes);
     }
   }
   if (Name == "AMD")
     return FindNote(AMDNoteTypes);
   if (Name == "AMDGPU")
     return FindNote(AMDGPUNoteTypes);
+  if (Name == "LLVMOMPOFFLOAD")
+    return FindNote(LLVMOMPOFFLOADNoteTypes);
 
   if (ELFType == ELF::ET_CORE)
     return FindNote(CoreNoteTypes);
   return FindNote(GenericNoteTypes);
 }
 
 template <class ELFT>
 static void printNotesHelper(
if (Name == "GNU") {
         return Error::success();
       }
     } else if (Name == "AMDGPU") {
       const AMDGPUNote N = getAMDGPUNote<ELFT>(Type, Descriptor);
       if (!N.Type.empty()) {
         OS << "    " << N.Type << ":\n        " << N.Value << '\n';
         return Error::success();
       }
+    } else if (Name == "LLVMOMPOFFLOAD") {
+      if (printLLVMOMPOFFLOADNote<ELFT>(OS, Type, Descriptor))
+        return Error::success();
     } else if (Name == "CORE") {
       if (Type == ELF::NT_FILE) {
         DataExtractor DescExtractor(Descriptor,
                                     ELFT::TargetEndianness == support::little,
                                     sizeof(Elf_Addr));
         if (Expected<CoreNote> NoteOrErr = readCoreNote(DescExtractor)) {
           printCoreNote<ELFT>(OS, *NoteOrErr);
           return Error::success();
case ELF::NT_GNU_ABI_TAG: {
     }
     break;
   }
   case ELF::NT_GNU_BUILD_ID: {
     W.printString("Build ID", getGNUBuildId(Desc));
     break;
   }
   case ELF::NT_GNU_GOLD_VERSION:
-    W.printString("Version", getGNUGoldVersion(Desc));
+    W.printString("Version", getDescAsStringRef(Desc));
     break;
   case ELF::NT_GNU_PROPERTY_TYPE_0:
     ListScope D(W, "Property");
     for (const std::string &Property : getGNUPropertyList<ELFT>(Desc))
       W.printString(Property);
     break;
   }
   return true;
 }
 
+template <typename ELFT>
+static bool printLLVMOMPOFFLOADNoteLLVMStyle(uint32_t NoteType,
+                                             ArrayRef<uint8_t> Desc,
+                                             ScopedPrinter &W) {
+  switch (NoteType) {
+  default:
+    return false;
+  case ELF::NT_LLVM_OPENMP_OFFLOAD_VERSION:
+    W.printString("Version", getDescAsStringRef(Desc));
+    break;
+  case ELF::NT_LLVM_OPENMP_OFFLOAD_PRODUCER:
+    W.printString("Producer", getDescAsStringRef(Desc));
+    break;
+  case ELF::NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION:
+    W.printString("Producer version", getDescAsStringRef(Desc));
+    break;
+  }
+  return true;
+}
+
 static void printCoreNoteLLVMStyle(const CoreNote &Note, ScopedPrinter &W) {
   W.printNumber("Page Size", Note.PageSize);
   for (const CoreFileMapping &Mapping : Note.Mappings) {
     ListScope D(W, "Mapping");
     W.printHex("Start", Mapping.Start);
     W.printHex("End", Mapping.End);
     W.printHex("Offset", Mapping.Offset);
     W.printString("Filename", Mapping.Filename);
if (Name == "GNU") {
         return Error::success();
       }
     } else if (Name == "AMDGPU") {
       const AMDGPUNote N = getAMDGPUNote<ELFT>(Type, Descriptor);
       if (!N.Type.empty()) {
         W.printString(N.Type, N.Value);
         return Error::success();
       }
+    } else if (Name == "LLVMOMPOFFLOAD") {
+      if (printLLVMOMPOFFLOADNoteLLVMStyle<ELFT>(Type, Descriptor, W))
+        return Error::success();
     } else if (Name == "CORE") {
       if (Type == ELF::NT_FILE) {
         DataExtractor DescExtractor(Descriptor,
                                     ELFT::TargetEndianness == support::little,
                                     sizeof(Elf_Addr));
         if (Expected<CoreNote> N = readCoreNote(DescExtractor)) {
           printCoreNoteLLVMStyle(*N, W);
           return Error::success();

openmp/libomptarget/plugins/amdgpu/CMakeLists.txt

 install(TARGETS omptarget.rtl.amdgpu LIBRARY DESTINATION "lib${OPENMP_LIBDIR_SUFFIX}")
 
 set_property(TARGET omptarget.rtl.amdgpu PROPERTY INSTALL_RPATH "$ORIGIN")
 target_link_libraries(
   omptarget.rtl.amdgpu
   PRIVATE
   elf_common
   hsa-runtime64::hsa-runtime64
-  pthread dl elf
+  dl
+  ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES}
+  ${OPENMP_PTHREAD_LIB}
   "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../exports"
   "-Wl,-z,defs"
   )
 
 # Report to the parent scope that we are building a plugin for amdgpu
 set(LIBOMPTARGET_SYSTEM_TARGETS "${LIBOMPTARGET_SYSTEM_TARGETS} amdgcn-amd-amdhsa" PARENT_SCOPE)
 

openmp/libomptarget/plugins/common/elf_common/CMakeLists.txt

 ##===----------------------------------------------------------------------===##
 #
 # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #
 ##===----------------------------------------------------------------------===##
 #
 # Common ELF functionality for target plugins
 #
 ##===----------------------------------------------------------------------===##
 
-add_library(elf_common INTERFACE)
+# Use libelf, is possible.
+# Otherwise, use LLVM ELF (unless OPENMP_STANDALONE_BUILD).
+set(MAY_USE_LIBELF LIBOMPTARGET_DEP_LIBELF_FOUND)
 
+option(LIBOMPTARGET_FORCE_LLVM_ELF
+  "Use LLVM ELFObjectFile implementation for elf_common.\
+  This requires in-tree build." OFF)
+add_library(elf_common OBJECT elf_common.cpp elf_light.cpp)
+
+if(MAY_USE_LIBELF AND NOT LIBOMPTARGET_FORCE_LLVM_ELF)
+  target_compile_definitions(elf_common PRIVATE -DMAY_USE_LIBELF)
+  target_include_directories(elf_common PRIVATE
+    ${LIBOMPTARGET_DEP_LIBELF_INCLUDE_DIR})
+  target_link_libraries(elf_common INTERFACE
+    ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES})
+elseif(NOT OPENMP_STANDALONE_BUILD)
+  llvm_update_compile_flags(elf_common)
+  target_link_libraries(elf_common INTERFACE
+    LLVMBinaryFormat LLVMObject LLVMSupport)
+else(MAY_USE_LIBELF AND NOT LIBOMPTARGET_FORCE_LLVM_ELF)
+  libomptarget_say("Not building elf_common offload plugin library: libelf dependency not found.")
+endif(MAY_USE_LIBELF AND NOT LIBOMPTARGET_FORCE_LLVM_ELF)
+
+# The code uses Debug.h, which requires threads support.
+target_link_libraries(elf_common INTERFACE ${OPENMP_PTHREAD_LIB})
+
+# Expose elf_common.h directory to the users of this library.
 target_include_directories(elf_common INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})

openmp/libomptarget/plugins/common/elf_common/elf_common.h

-//===-- elf_common.h - Common ELF functionality -------------------*- C -*-===//
+//===-- elf_common.h - Common ELF functionality -----------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // Common ELF functionality for target plugins.
-// Must be included in the plugin source file AFTER omptarget.h has been
-// included and macro DP(...) has been defined.
-// .
 //
 //===----------------------------------------------------------------------===//
 
-#if !(defined(_OMPTARGET_DEBUG_H))
-#error Include elf_common.h in the plugin source AFTER Debug.h has\
- been included.
-#endif
+#ifndef LIBOMPTARGET_PLUGINS_ELF_COMMON_H
+#define LIBOMPTARGET_PLUGINS_ELF_COMMON_H
 
-#include <elf.h>
-#include <libelf.h>
+#include <cstdint>
+#include "elf_constants.h"
+#include "omptargetplugin.h"
+
+/// Return non-zero, if the given \p image is an ELF object, which
+/// e_machine matches \p target_id; return zero otherwise.
+EXTERN int32_t elf_check_machine(__tgt_device_image *image,
+                                 uint16_t target_id);
+
+/// Return non-zero, if the given \p image is an ET_DYN ELF object;
+/// return zero otherwise.
+EXTERN int32_t elf_is_dynamic(__tgt_device_image *image);
 
-// Check whether an image is valid for execution on target_id
-static inline int32_t elf_check_machine(__tgt_device_image *image,
-                                        uint16_t target_id) {
-
-  // Is the library version incompatible with the header file?
-  if (elf_version(EV_CURRENT) == EV_NONE) {
-    DP("Incompatible ELF library!\n");
-    return 0;
-  }
-
-  char *img_begin = (char *)image->ImageStart;
-  char *img_end = (char *)image->ImageEnd;
-  size_t img_size = img_end - img_begin;
-
-  // Obtain elf handler
-  Elf *e = elf_memory(img_begin, img_size);
-  if (!e) {
-    DP("Unable to get ELF handle: %s!\n", elf_errmsg(-1));
-    return 0;
-  }
-
-  // Check if ELF is the right kind.
-  if (elf_kind(e) != ELF_K_ELF) {
-    DP("Unexpected ELF type!\n");
-    elf_end(e);
-    return 0;
-  }
-  Elf64_Ehdr *eh64 = elf64_getehdr(e);
-  Elf32_Ehdr *eh32 = elf32_getehdr(e);
-
-  if (!eh64 && !eh32) {
-    DP("Unable to get machine ID from ELF file!\n");
-    elf_end(e);
-    return 0;
-  }
-
-  uint16_t MachineID;
-  if (eh64 && !eh32)
-    MachineID = eh64->e_machine;
-  else if (eh32 && !eh64)
-    MachineID = eh32->e_machine;
-  else {
-    DP("Ambiguous ELF header!\n");
-    elf_end(e);
-    return 0;
-  }
-
-  elf_end(e);
-  return MachineID == target_id;
-}
-
-static inline int32_t elf_is_dynamic(__tgt_device_image *image) {
-
-  char *img_begin = (char *)image->ImageStart;
-  char *img_end = (char *)image->ImageEnd;
-  size_t img_size = img_end - img_begin;
-
-  // Obtain elf handler
-  Elf *e = elf_memory(img_begin, img_size);
-  if (!e) {
-    DP("Unable to get ELF handle: %s!\n", elf_errmsg(-1));
-    return 0;
-  }
-
-  Elf64_Ehdr *eh64 = elf64_getehdr(e);
-  Elf32_Ehdr *eh32 = elf32_getehdr(e);
-
-  if (!eh64 && !eh32) {
-    DP("Unable to get machine ID from ELF file!\n");
-    elf_end(e);
-    return 0;
-  }
-
-  uint16_t Type;
-  if (eh64 && !eh32)
-    Type = eh64->e_type;
-  else if (eh32 && !eh64)
-    Type = eh32->e_type;
-  else {
-    DP("Ambiguous ELF header!\n");
-    elf_end(e);
-    return 0;
-  }
-
-  elf_end(e);
-  DP("ELF Type: %d\n", Type);
-  return Type == ET_DYN;
-}
+#endif // LIBOMPTARGET_PLUGINS_ELF_COMMON_H

openmp/libomptarget/plugins/common/elf_common/elf_common.cpp

+//===-- elf_common.cpp - Common ELF functionality -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Common ELF functionality for target plugins.
+//
+//===----------------------------------------------------------------------===//
+#include "Debug.h"
+#include "elf_common.h"
+#include "elf_light.h"
+
+#ifndef TARGET_NAME
+#define TARGET_NAME Common ELF
+#endif
+#define DEBUG_PREFIX "TARGET " GETNAME(TARGET_NAME)
+
+#ifdef ELFMAG
+// Subtle verification that libelf APIs are not used explicitly here.
+// Code here must use libelf independent APIs from elf_light.h.
+#error "LIBELF.H cannot be used explicitly here."
+#endif // ELFMAG
+
+EXTERN int32_t elf_check_machine(__tgt_device_image *image,
+                                 uint16_t target_id) {
+  char *img_begin = reinterpret_cast<char *>(image->ImageStart);
+  char *img_end = reinterpret_cast<char *>(image->ImageEnd);
+  size_t img_size = img_end - img_begin;
+  ElfL E(img_begin, img_size);
+  if (!E.isValidElf()) {
+    DP("Unable to get ELF handle: %s!\n", E.getErrmsg(-1));
+    return 0;
+  }
+
+  if (getDebugLevel() > 0) {
+    auto PrintOutNote = [](const ElfLNote &Note) {
+      if (Note.getNameSize() == 0)
+        return;
+
+      std::string NameStr(Note.getName(), Note.getNameSize());
+      // Check if this is a null-terminated "LLVMOMPOFFLOAD" string.
+      std::string LlvmName("LLVMOMPOFFLOAD");
+      LlvmName += '\0';
+      if (NameStr != LlvmName)
+        return;
+
+      uint64_t Type = Note.getType();
+      switch (Type) {
+      default:
+        DP("LLVMOMPOFFLOAD ELF note with unknown type %" PRIu64 ".\n", Type);
+        break;
+      case NT_LLVM_OPENMP_OFFLOAD_VERSION:
+      case NT_LLVM_OPENMP_OFFLOAD_PRODUCER:
+      case NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION: {
+        std::string DescStr(reinterpret_cast<const char *>(Note.getDesc()),
+                            Note.getDescSize());
+        DP("LLVMOMPOFFLOAD ELF note %s with value: '%s'\n",
+           OMPNoteTypeNames[Type], DescStr.c_str());
+        break;
+      }
+      }
+    };
+
+    for (auto I = E.section_notes_begin(), IE = E.section_notes_end();
+         I != IE; ++I)
+      PrintOutNote(*I);
+
+    for (auto I = E.segment_notes_begin(), IE = E.segment_notes_end();
+         I != IE; ++I)
+      PrintOutNote(*I);
+  }
+  uint16_t MachineID = E.getEMachine();
+  return MachineID == target_id;
+}
+
+EXTERN int32_t elf_is_dynamic(__tgt_device_image *image) {
+  char *img_begin = reinterpret_cast<char *>(image->ImageStart);
+  char *img_end = reinterpret_cast<char *>(image->ImageEnd);
+  size_t img_size = img_end - img_begin;
+  ElfL E(img_begin, img_size);
+  if (!E.isValidElf()) {
+    DP("Unable to get ELF handle: %s!\n", E.getErrmsg(-1));
+    return 0;
+  }
+
+  uint16_t Type = E.getEType();
+  DP("ELF Type: %" PRIu16 "\n", Type);
+  return ElfL::isDynType(Type);
+}

openmp/libomptarget/plugins/common/elf_common/elf_constants.h

+//===-- elf_constants.h - ELF constants -------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Here we duplicate some ELF constants that may not be yet available
+// in elf.h or llvm/BinaryFormat/ELF.h (e.g. in an out-of-tree build).
+// Note that we use the same constant names as in llvm/BinaryFormat/ELF.h.
+//
+//===----------------------------------------------------------------------===//
+
+// ELF notes with "LLVMOMPOFFLOAD" name may be of either of these types.
+enum : unsigned {
+  NT_LLVM_OPENMP_OFFLOAD_VERSION = 1,
+  NT_LLVM_OPENMP_OFFLOAD_PRODUCER = 2,
+  NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION = 3,
+  NT_LLVM_OPENMP_OFFLOAD_LAST = NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION
+};
+
+constexpr const char *OMPNoteTypeNames[NT_LLVM_OPENMP_OFFLOAD_LAST + 1] = {
+  "NT_LLVM_OPENMP_OFFLOAD_UNKNOWN",
+  "NT_LLVM_OPENMP_OFFLOAD_VERSION",
+  "NT_LLVM_OPENMP_OFFLOAD_PRODUCER",
+  "NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION",
+};

openmp/libomptarget/plugins/common/elf_common/elf_light.h

+//===-- elf_light.h - Basic ELF functionality -------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Light ELF implementation provides basic ELF reading functionality.
+// It may be used in systems without libelf support, if the corresponding
+// LLVM ELF implementation is available.
+// The interface declared here must be independent of libelf.h/elf.h.
+//
+// NOTE: we can try to rely on https://github.com/WolfgangSt/libelf
+//       on Windows, if this implementation gets more complex.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LIBOMPTARGET_PLUGINS_ELF_LIGHT_H
+#define LIBOMPTARGET_PLUGINS_ELF_LIGHT_H
+
+#include <cstddef>
+#include <cstdint>
+#include <iterator>
+
+class ElfL;
+class ElfLSegmentNoteIterator;
+class ElfLSectionNoteIterator;
+class ElfNote;
+
+// Class representing NOTEs from PT_NOTE segments and SHT_NOTE sections.
+class ElfLNote {
+  const void *Impl = nullptr;
+
+  friend class ElfLSegmentNoteIterator;
+  friend class ElfLSectionNoteIterator;
+
+  // Only ElfLSectionNoteIterator is allowed to create notes via its operator*().
+  explicit ElfLNote(const void *I);
+  ElfLNote &operator=(const ElfLNote &) = delete;
+
+public:
+  // FIXME: add move copy constructor and assignment operator.
+  ElfLNote(const ElfLNote &);
+  ~ElfLNote();
+  uint64_t getNameSize() const;
+  const char *getName() const;
+  uint64_t getDescSize() const;
+  const uint8_t *getDesc() const;
+  uint64_t getType() const;
+};
+
+// Iterator over NOTEs in PT_NOTE segments.
+class ElfLSegmentNoteIterator
+    : std::iterator<std::forward_iterator_tag, ElfLNote> {
+
+  void *Impl = nullptr;
+
+  friend class ElfL;
+
+  // Only ElfL is allowed to create iterators to itself.
+  ElfLSegmentNoteIterator(const void *I, bool IsEnd = false);
+  ElfLSectionNoteIterator &operator=(const ElfLSegmentNoteIterator &) = delete;
+
+public:
+  // FIXME: add move copy constructor and assignment operator.
+  ElfLSegmentNoteIterator(const ElfLSegmentNoteIterator &Other);
+  ~ElfLSegmentNoteIterator();
+  ElfLSegmentNoteIterator &operator++();
+  bool operator==(const ElfLSegmentNoteIterator Other) const;
+  bool operator!=(const ElfLSegmentNoteIterator Other) const;
+  ElfLNote operator*() const;
+};
+
+// Iterator over NOTEs in SHT_NOTE sections.
+class ElfLSectionNoteIterator
+    : std::iterator<std::forward_iterator_tag, ElfLNote> {
+
+  void *Impl = nullptr;
+
+  friend class ElfL;
+
+  // Only ElfL is allowed to create iterators to itself.
+  ElfLSectionNoteIterator(const void *I, bool IsEnd = false);
+  ElfLSectionNoteIterator &operator=(const ElfLSectionNoteIterator &) = delete;
+
+public:
+  // FIXME: add move copy constructor and assignment operator.
+  ElfLSectionNoteIterator(const ElfLSectionNoteIterator &Other);
+  ~ElfLSectionNoteIterator();
+  ElfLSectionNoteIterator &operator++();
+  bool operator==(const ElfLSectionNoteIterator Other) const;
+  bool operator!=(const ElfLSectionNoteIterator Other) const;
+  ElfLNote operator*() const;
+};
+
+// Wrapper around the given ELF image.
+class ElfL {
+  // Opaque pointer to the actual implementation.
+  void *Impl = nullptr;
+
+  // FIXME: implement if needed.
+  ElfL(const ElfL &) = delete;
+  ElfL &operator=(const ElfL &) = delete;
+
+public:
+  ElfL(char *Begin, size_t Size);
+  ~ElfL();
+  bool isValidElf() const;
+  const char *getErrmsg(int N) const;
+  uint16_t getEMachine() const;
+  uint16_t getEType() const;
+
+  static bool isDynType(uint16_t Ty);
+
+  ElfLSectionNoteIterator section_notes_begin() const;
+  ElfLSectionNoteIterator section_notes_end() const;
+  ElfLSegmentNoteIterator segment_notes_begin() const;
+  ElfLSegmentNoteIterator segment_notes_end() const;
+};
+
+#endif  // LIBOMPTARGET_PLUGINS_ELF_LIGHT_H

openmp/libomptarget/plugins/common/elf_common/elf_light.cpp

+//===-- elf_light.cpp - Basic ELF functionality -----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <assert.h>
+#include "Debug.h"
+#include "elf_light.h"
+
+#ifndef TARGET_NAME
+#define TARGET_NAME ELF light
+#endif
+#define DEBUG_PREFIX "TARGET " GETNAME(TARGET_NAME)
+
+#if MAY_USE_LIBELF
+
+// Implementation based on libelf.
+#include <gelf.h>
+#include <libelf.h>
+
+// Helper methods to align addresses.
+template <typename T> inline T alignDown(T value, size_t alignment) {
+  return (T)(value & ~(alignment - 1));
+}
+
+template <typename T> inline T *alignDown(T *value, size_t alignment) {
+  return reinterpret_cast<T *>(alignDown((intptr_t)value, alignment));
+}
+
+template <typename T> inline T alignUp(T value, size_t alignment) {
+  return alignDown((T)(value + alignment - 1), alignment);
+}
+
+template <typename T> inline T *alignUp(T *value, size_t alignment) {
+  return reinterpret_cast<T *>(
+      alignDown((intptr_t)(value + alignment - 1), alignment));
+}
+
+// FIXME: this is taken from openmp/libomptarget/plugins/amdgpu/impl/system.cpp,
+//        but it may be incorrect for 64-bit ELF. Elf64_Nhdr and Elf32_Nhdr
+//        have different representation. The alignment used for the name and
+//        the descriptor is still 4 bytes. At the same time, it seems to work
+//        for 64-bit ELFs produced by LLVM.
+typedef struct {
+  uint32_t n_namesz; // Length of note's name.
+  uint32_t n_descsz; // Length of note's value.
+  uint32_t n_type;   // Type of note.
+  // then name
+  // then padding, optional
+  // then desc, at 4 byte alignment (not 8, despite being elf64)
+} Elf_Note;
+
+static const uint32_t NoteAlignment = 4;
+
+// Implementation of the iterator for SHT_NOTE sections.
+// The iterator allows processing all NOTEs in all SHT_NOTE sections
+// in the ELF image provided during the iterator object construction.
+class ElfLSectionNoteIteratorImpl {
+  // A pointer to Elf object created by elf_memory() for
+  // the ELF image we are going to iterate.
+  Elf *EF;
+
+  // A pointer to the current SHT_NOTE section.
+  // In the initial state of the iterator object this will actually
+  // point to the very first section in the ELF image, but it will be
+  // adjusted right away either to point to the first SHT_NOTE section
+  // or set to nullptr (if there are no SHT_NOTE sections).
+  Elf_Scn *CurrentSection = nullptr;
+
+  // A pointer to the current NOTE inside a SHT_NOTE section
+  // pointed by CurrentSection. If it is nullptr, then this means
+  // that the iterator object is an end() iterator.
+  Elf_Note *NPtr = nullptr;
+
+  uint64_t getNotesBeginAddr(const GElf_Shdr &Shdr) const {
+    return reinterpret_cast<uint64_t>(elf_rawfile(EF, nullptr)) +
+        Shdr.sh_offset;
+  }
+
+  uint64_t getNotesEndAddr(const GElf_Shdr &Shdr) const {
+    return getNotesBeginAddr(Shdr) + Shdr.sh_size;
+  }
+
+  uint64_t getNoteSize(const Elf_Note &Note) const {
+    return sizeof(Note) + alignUp(Note.n_namesz, NoteAlignment) +
+        alignUp(Note.n_descsz, NoteAlignment);
+  }
+
+  // Given the current state of the iterator object, advances
+  // the iterator forward to point to the next NOTE in the next
+  // SHT_NOTE section.
+  // If there is no such a NOTE, then it sets the iterator
+  // object to the end() state.
+  //
+  // Note that this method does not change the iterator, if
+  // NPtr is pointing to a valid note within CurrentSection.
+  // The iterator advancement in this case is done via operator++.
+  void autoAdvance(bool IsFirst = false) {
+    // Cannot advance, if CurrentSection is NULL.
+    if (!CurrentSection)
+      return;
+
+    // NPtr points to a valid NOTE in CurrentSection, thus,
+    // no auto advancement.
+    if (NPtr)
+      return;
+
+    GElf_Shdr Shdr;
+    gelf_getshdr(CurrentSection, &Shdr);
+
+    // CurrentSection is a valid section, and NPtr is an end() iterator.
+    //
+    // If IsFirst is true, then we just in the initial state, and
+    // we need to set CurrentSection to the first SHT_NOTE section (if any),
+    // and, then, NPtr to the first note in this section.
+    //
+    // If IsFirst is false, then we've reached the end of the current
+    // SHT_NOTE section, and should find the next section with notes.
+    if (!IsFirst ||
+        gelf_getshdr(CurrentSection, &Shdr)->sh_type != SHT_NOTE)
+      CurrentSection = elf_nextscn(EF, CurrentSection);
+
+    while (CurrentSection &&
+           gelf_getshdr(CurrentSection, &Shdr)->sh_type != SHT_NOTE)
+      CurrentSection = elf_nextscn(EF, CurrentSection);
+
+    if (!CurrentSection) {
+      // No more sections.
+      // Note that NPtr is already nullptr indicating the end() iterator.
+      return;
+    }
+
+    gelf_getshdr(CurrentSection, &Shdr);
+    uint64_t NotesBegin = getNotesBeginAddr(Shdr);
+    uint64_t NotesEnd = getNotesEndAddr(Shdr);
+    if (NotesBegin >= NotesEnd) {
+      // Something went wrong. Assume that we've reached
+      // the end of all notes.
+      CurrentSection = nullptr;
+      NPtr = nullptr;
+      return;
+    }
+
+    NPtr = reinterpret_cast<Elf_Note *>(NotesBegin);
+    assert(NPtr && "Invalid SHT_NOTE section.");
+  }
+
+  bool operator!=(const ElfLSectionNoteIteratorImpl Other) const {
+    return !(*this == Other);
+  }
+
+public:
+  ElfLSectionNoteIteratorImpl(Elf *RawElf, bool IsEnd = false)
+    : EF(RawElf) {
+    assert(EF && "Trying to iterate invalid ELF.");
+
+    if (IsEnd) {
+      // NPtr equal to nullptr means end() iterator.
+      return;
+    }
+
+    // Set CurrentSection to the very first section,
+    // and let autoAdvance() find the first valid note (if any).
+    CurrentSection = elf_getscn(EF, 0);
+    autoAdvance(true);
+  }
+
+  bool operator==(const ElfLSectionNoteIteratorImpl Other) const {
+    // They should be pointing to the same NOTE to be equal.
+    return NPtr == Other.NPtr;
+  }
+
+  const Elf_Note *operator*() const {
+    assert(*this != ElfLSectionNoteIteratorImpl(EF, true) &&
+           "Dereferencing the end iterator.");
+    return NPtr;
+  }
+
+  // Advance to the next NOTE in the CurrentSection.
+  // If there is no next NOTE, then autoAdvance() to the next
+  // SHT_NOTE section and its first NOTE.
+  ElfLSectionNoteIteratorImpl &operator++() {
+    assert(*this != ElfLSectionNoteIteratorImpl(EF, true) &&
+           "Incrementing the end iterator.");
+
+    GElf_Shdr Shdr;
+    gelf_getshdr(CurrentSection, &Shdr);
+    uint64_t NotesBegin = getNotesBeginAddr(Shdr);
+    uint64_t NotesEnd = getNotesEndAddr(Shdr);
+    assert(reinterpret_cast<uint64_t>(NPtr) >= NotesBegin &&
+           reinterpret_cast<uint64_t>(NPtr) < NotesEnd &&
+           "Invalid pointer to a note computed somewhere else.");
+
+    uint64_t NoteSize = getNoteSize(*NPtr);
+    NPtr = reinterpret_cast<Elf_Note *>(reinterpret_cast<char *>(NPtr) +
+                                        NoteSize);
+    if (reinterpret_cast<uint64_t>(NPtr) >= NotesEnd ||
+        reinterpret_cast<uint64_t>(NPtr) + sizeof(*NPtr) >= NotesEnd) {
+      // We've reached the end of the current NOTE section.
+      NPtr = nullptr;
+    }
+
+    // Auto advance to the next section, if needed.
+    autoAdvance();
+    return *this;
+  }
+};
+
+// Implementation of the iterator for PT_NOTE segments.
+// The iterator allows processing all NOTEs in all PT_NOTE segments
+// in the ELF image provided during the iterator object construction.
+class ElfLSegmentNoteIteratorImpl {
+  // A pointer to Elf object created by elf_memory() for
+  // the ELF image we are going to iterate.
+  Elf *EF;
+
+  // A pointer to the current PT_NOTE segment.
+  // In the initial state of the iterator object this will actually
+  // point to the very first segment in the ELF image, but it will be
+  // adjusted right away either to point to the first PT_NOTE segment
+  // or set to nullptr (if there are no PT_NOTE segments).
+  size_t NumberOfPhdrs = (std::numeric_limits<size_t>::max)();
+  size_t CurrentSegment = (std::numeric_limits<size_t>::max)();
+
+  // A pointer to the current NOTE inside a PT_NOTE segment
+  // pointed by CurrentSegment. If it is nullptr, then this means
+  // that the iterator object is an end() iterator.
+  Elf_Note *NPtr = nullptr;
+
+  uint64_t getNotesBeginAddr(const GElf_Phdr &Phdr) const {
+    return reinterpret_cast<uint64_t>(elf_rawfile(EF, nullptr)) +
+        Phdr.p_offset;
+  }
+
+  uint64_t getNotesEndAddr(const GElf_Phdr &Phdr) const {
+    return getNotesBeginAddr(Phdr) + Phdr.p_filesz;
+  }
+
+  uint64_t getNoteSize(const Elf_Note &Note) const {
+    return sizeof(Note) + alignUp(Note.n_namesz, NoteAlignment) +
+        alignUp(Note.n_descsz, NoteAlignment);
+  }
+
+  // Given the current state of the iterator object, advances
+  // the iterator forward to point to the next NOTE in the next
+  // PT_NOTE segment.
+  // If there is no such a NOTE, then it sets the iterator
+  // object to the end() state.
+  //
+  // Note that this method does not change the iterator, if
+  // NPtr is pointing to a valid note within CurrentSegment.
+  // The iterator advancement in this case is done via operator++.
+  void autoAdvance(bool IsFirst = false) {
+    // Cannot advance, if CurrentSegment is invalid.
+    if (CurrentSegment >= NumberOfPhdrs)
+      return;
+
+    // NPtr points to a valid NOTE in CurrentSegment, thus,
+    // no auto advancement.
+    if (NPtr)
+      return;
+
+    GElf_Phdr Phdr;
+    gelf_getphdr(EF, CurrentSegment, &Phdr);
+
+    // CurrentSegment is a valid segment, and NPtr is an end() iterator.
+    //
+    // If IsFirst is true, then we just in the initial state, and
+    // we need to set CurrentSegment to the first PT_NOTE segment (if any),
+    // and, then, NPtr to the first note in this segment.
+    //
+    // If IsFirst is false, then we've reached the end of the current
+    // PT_NOTE segment, and should find the next segment with notes.
+    if (!IsFirst || Phdr.p_type != PT_NOTE)
+      ++CurrentSegment;
+
+    while (CurrentSegment < NumberOfPhdrs) {
+      if (gelf_getphdr(EF, CurrentSegment, &Phdr) != &Phdr)
+        continue;
+
+      if (Phdr.p_type == PT_NOTE)
+        break;
+
+      ++CurrentSegment;
+    }
+
+    if (CurrentSegment >= NumberOfPhdrs) {
+      // No more segments.
+      // Note that NPtr is already nullptr indicating the end() iterator.
+      return;
+    }
+
+    if (gelf_getphdr(EF, CurrentSegment, &Phdr) != &Phdr)
+      assert("Invalid program header selected above.");
+
+    uint64_t NotesBegin = getNotesBeginAddr(Phdr);
+    uint64_t NotesEnd = getNotesEndAddr(Phdr);
+    if (NotesBegin >= NotesEnd) {
+      // Something went wrong. Assume that we've reached
+      // the end of all notes.
+      CurrentSegment = NumberOfPhdrs;
+      NPtr = nullptr;
+      return;
+    }
+
+    NPtr = reinterpret_cast<Elf_Note *>(NotesBegin);
+    assert(NPtr && "Invalid PT_NOTE segment.");
+  }
+
+  bool operator!=(const ElfLSegmentNoteIteratorImpl Other) const {
+    return !(*this == Other);
+  }
+
+public:
+  ElfLSegmentNoteIteratorImpl(Elf *RawElf, bool IsEnd = false)
+    : EF(RawElf) {
+    assert(EF && "Trying to iterate invalid ELF.");
+
+    if (IsEnd) {
+      // NPtr equal to nullptr means end() iterator.
+      return;
+    }
+
+    // Set CurrentSegment to the very first segment,
+    // and let autoAdvance() find the first valid note (if any).
+    CurrentSegment = 0;
+
+    // Set NumberOfPhdrs to 0, if we cannot query it.
+    if (elf_getphdrnum(EF, &NumberOfPhdrs) != 0)
+      NumberOfPhdrs = 0;
+    autoAdvance(true);
+  }
+
+  bool operator==(const ElfLSegmentNoteIteratorImpl Other) const {
+    // They should be pointing to the same NOTE to be equal.
+    return NPtr == Other.NPtr;
+  }
+
+  const Elf_Note *operator*() const {
+    assert(*this != ElfLSegmentNoteIteratorImpl(EF, true) &&
+           "Dereferencing the end iterator.");
+    return NPtr;
+  }
+
+  // Advance to the next NOTE in the CurrentSegment.
+  // If there is no next NOTE, then autoAdvance() to the next
+  // PT_NOTE segment and its first NOTE.
+  ElfLSegmentNoteIteratorImpl &operator++() {
+    assert(*this != ElfLSegmentNoteIteratorImpl(EF, true) &&
+           "Incrementing the end iterator.");
+
+    GElf_Phdr Phdr;
+    gelf_getphdr(EF, CurrentSegment, &Phdr);
+    uint64_t NotesBegin = getNotesBeginAddr(Phdr);
+    uint64_t NotesEnd = getNotesEndAddr(Phdr);
+    assert(reinterpret_cast<uint64_t>(NPtr) >= NotesBegin &&
+           reinterpret_cast<uint64_t>(NPtr) < NotesEnd &&
+           "Invalid pointer to a note computed somewhere else.");
+
+    uint64_t NoteSize = getNoteSize(*NPtr);
+    NPtr = reinterpret_cast<Elf_Note *>(reinterpret_cast<char *>(NPtr) +
+                                        NoteSize);
+    if (reinterpret_cast<uint64_t>(NPtr) >= NotesEnd ||
+        reinterpret_cast<uint64_t>(NPtr) + sizeof(*NPtr) >= NotesEnd) {
+      // We've reached the end of the current NOTE section.
+      NPtr = nullptr;
+    }
+
+    // Auto advance to the next section, if needed.
+    autoAdvance();
+    return *this;
+  }
+};
+
+// Actual implementation of ElfL via libelf.
+// It is constructed from an ELF image defined by its
+// starting pointer in memory and a length in bytes.
+class ElfLImpl {
+  // A pointer to Elf object created by elf_memory() for
+  // the ELF image.
+  Elf *EF = nullptr;
+
+  // Class of the ELF image.
+  unsigned ElfClass = ELFCLASSNONE;
+
+  // A pointer to the ELF image's header.
+  // Depending on the class it may be either 'Elf32_Ehdr *'
+  // or 'Elf64_Ehdr '.
+  const void *Header = nullptr;  
+
+  // Let the owning object access this.
+  friend class ElfL;
+
+public:
+  ElfLImpl(Elf *RawElf, unsigned ElfClass, const void *Header)
+    : EF(RawElf), ElfClass(ElfClass), Header(Header) {}
+
+  // Allocates and constructs a new iterator for NOTEs in
+  // SHT_NOTE sections of the ELF image.
+  ElfLSectionNoteIteratorImpl *create_section_note_iterator_impl(bool IsEnd) const {
+    return new ElfLSectionNoteIteratorImpl(EF, IsEnd);
+  }
+
+  // Allocates and constructs a new iterator for NOTEs in
+  // PT_NOTE segments of the ELF image.
+  ElfLSegmentNoteIteratorImpl *create_segment_note_iterator_impl(bool IsEnd) const {
+    return new ElfLSegmentNoteIteratorImpl(EF, IsEnd);
+  }
+};
+
+ElfL::ElfL(char *Begin, size_t Size) {
+  Elf *ElfHandle = elf_memory(Begin, Size);
+  if (!ElfHandle) {
+    elf_end(ElfHandle);
+    return;
+  }
+
+  const Elf32_Ehdr *Header32 = elf32_getehdr(ElfHandle);
+  const Elf64_Ehdr *Header64 = elf64_getehdr(ElfHandle);
+
+  if (!Header32 == !Header64) {
+    // Ambiguous ELF header or unrecognized ELF image.
+    elf_end(ElfHandle);
+    return;
+  }
+
+  const void *Header = nullptr;
+  unsigned ElfClass = ELFCLASSNONE;
+
+  if (Header32) {
+    ElfClass = ELFCLASS32;
+    Header = reinterpret_cast<const void *>(Header32);
+  } else {
+    ElfClass = ELFCLASS64;
+    Header = reinterpret_cast<const void *>(Header64);
+  }
+
+  Impl = reinterpret_cast<void *>(new ElfLImpl(ElfHandle, ElfClass, Header));
+}
+
+ElfL::~ElfL() {
+  if (Impl) {
+    ElfLImpl *EImpl = reinterpret_cast<ElfLImpl *>(Impl);
+    elf_end(EImpl->EF);
+    delete EImpl;
+  }
+}
+
+bool ElfL::isValidElf() const {
+  ElfLImpl *EImpl = reinterpret_cast<ElfLImpl *>(Impl);
+  return Impl && EImpl->Header && EImpl->ElfClass != ELFCLASSNONE;
+}
+
+const char *ElfL::getErrmsg(int N) const {
+  return elf_errmsg(-1);
+}
+
+uint16_t ElfL::getEMachine() const {
+  assert(isValidElf() && "Invalid ELF.");
+  ElfLImpl *EImpl = reinterpret_cast<ElfLImpl *>(Impl);
+  if (EImpl->ElfClass == ELFCLASS32)
+    return reinterpret_cast<const Elf32_Ehdr *>(EImpl->Header)->e_machine;
+  else if (EImpl->ElfClass == ELFCLASS64)
+    return reinterpret_cast<const Elf64_Ehdr *>(EImpl->Header)->e_machine;
+  else
+    assert("Unsupported ELF class.");
+
+  return EM_NONE;
+}
+
+uint16_t ElfL::getEType() const {
+  assert(isValidElf() && "Invalid ELF.");
+  ElfLImpl *EImpl = reinterpret_cast<ElfLImpl *>(Impl);
+  if (EImpl->ElfClass == ELFCLASS32)
+    return reinterpret_cast<const Elf32_Ehdr *>(EImpl->Header)->e_type;
+  else if (EImpl->ElfClass == ELFCLASS64)
+    return reinterpret_cast<const Elf64_Ehdr *>(EImpl->Header)->e_type;
+  else
+    assert("Unsupported ELF class.");
+
+  return ET_NONE;
+}
+
+bool ElfL::isDynType(uint16_t Ty) {
+  return Ty == ET_DYN;
+}
+
+ElfLSectionNoteIterator ElfL::section_notes_begin() const {
+  return ElfLSectionNoteIterator(reinterpret_cast<const ElfLImpl *>(Impl));
+}
+
+ElfLSectionNoteIterator ElfL::section_notes_end() const {
+  return ElfLSectionNoteIterator(reinterpret_cast<const ElfLImpl *>(Impl), true);
+}
+
+ElfLSectionNoteIterator::ElfLSectionNoteIterator(const void *I, bool IsEnd) {
+  const ElfLImpl *EImpl = reinterpret_cast<const ElfLImpl *>(I);
+  Impl = EImpl->create_section_note_iterator_impl(IsEnd);
+}
+
+ElfLSectionNoteIterator::ElfLSectionNoteIterator(const ElfLSectionNoteIterator &Other) {
+  ElfLSectionNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSectionNoteIteratorImpl *>(Other.Impl);
+  Impl = new ElfLSectionNoteIteratorImpl(*IImpl);
+}
+
+ElfLSectionNoteIterator::~ElfLSectionNoteIterator() {
+  assert(Impl && "Invalid ElfLSectionNoteIterator object.");
+  ElfLSectionNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSectionNoteIteratorImpl *>(Impl);
+  delete IImpl;
+}
+
+bool ElfLSectionNoteIterator::operator==(const ElfLSectionNoteIterator Other) const {
+  const ElfLSectionNoteIteratorImpl *Lhs =
+      reinterpret_cast<const ElfLSectionNoteIteratorImpl *>(Impl);
+  const ElfLSectionNoteIteratorImpl *Rhs =
+      reinterpret_cast<const ElfLSectionNoteIteratorImpl *>(Other.Impl);
+  return (*Lhs == *Rhs);
+}
+
+bool ElfLSectionNoteIterator::operator!=(const ElfLSectionNoteIterator Other) const {
+  return !(*this == Other);
+}
+
+ElfLSectionNoteIterator &ElfLSectionNoteIterator::operator++() {
+  ElfLSectionNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSectionNoteIteratorImpl *>(Impl);
+  ++(*IImpl);
+  return *this;
+}
+
+ElfLNote ElfLSectionNoteIterator::operator*() const {
+  ElfLSectionNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSectionNoteIteratorImpl *>(Impl);
+  return ElfLNote(**IImpl);
+}
+
+ElfLSegmentNoteIterator ElfL::segment_notes_begin() const {
+  return ElfLSegmentNoteIterator(reinterpret_cast<const ElfLImpl *>(Impl));
+}
+
+ElfLSegmentNoteIterator ElfL::segment_notes_end() const {
+  return ElfLSegmentNoteIterator(reinterpret_cast<const ElfLImpl *>(Impl), true);
+}
+
+ElfLSegmentNoteIterator::ElfLSegmentNoteIterator(const void *I, bool IsEnd) {
+  const ElfLImpl *EImpl = reinterpret_cast<const ElfLImpl *>(I);
+  Impl = EImpl->create_segment_note_iterator_impl(IsEnd);
+}
+
+ElfLSegmentNoteIterator::ElfLSegmentNoteIterator(const ElfLSegmentNoteIterator &Other) {
+  ElfLSegmentNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSegmentNoteIteratorImpl *>(Other.Impl);
+  Impl = new ElfLSegmentNoteIteratorImpl(*IImpl);
+}
+
+ElfLSegmentNoteIterator::~ElfLSegmentNoteIterator() {
+  assert(Impl && "Invalid ElfLSegmentNoteIterator object.");
+  ElfLSegmentNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSegmentNoteIteratorImpl *>(Impl);
+  delete IImpl;
+}
+
+bool ElfLSegmentNoteIterator::operator==(const ElfLSegmentNoteIterator Other) const {
+  const ElfLSegmentNoteIteratorImpl *Lhs =
+      reinterpret_cast<const ElfLSegmentNoteIteratorImpl *>(Impl);
+  const ElfLSegmentNoteIteratorImpl *Rhs =
+      reinterpret_cast<const ElfLSegmentNoteIteratorImpl *>(Other.Impl);
+  return (*Lhs == *Rhs);
+}
+
+bool ElfLSegmentNoteIterator::operator!=(const ElfLSegmentNoteIterator Other) const {
+  return !(*this == Other);
+}
+
+ElfLSegmentNoteIterator &ElfLSegmentNoteIterator::operator++() {
+  ElfLSegmentNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSegmentNoteIteratorImpl *>(Impl);
+  ++(*IImpl);
+  return *this;
+}
+
+ElfLNote ElfLSegmentNoteIterator::operator*() const {
+  ElfLSegmentNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSegmentNoteIteratorImpl *>(Impl);
+  return ElfLNote(**IImpl);
+}
+
+ElfLNote::ElfLNote(const void *I) {
+  // ElfLNote::Impl is a pointer to Elf_Note in this implementation.
+  // A pointer to Elf_Note is returned by ElfLSectionNoteIteratorImpl::operator*().
+  Impl = I;
+}
+
+ElfLNote::ElfLNote(const ElfLNote &Other) {
+  Impl = Other.Impl;
+}
+
+ElfLNote::~ElfLNote() {}
+
+uint64_t ElfLNote::getNameSize() const {
+  const Elf_Note *Note = reinterpret_cast<const Elf_Note *>(Impl);
+  return Note->n_namesz;
+}
+
+const char *ElfLNote::getName() const {
+  const Elf_Note *Note = reinterpret_cast<const Elf_Note *>(Impl);
+  return reinterpret_cast<const char *>(Note) + sizeof(*Note);
+}
+
+uint64_t ElfLNote::getDescSize() const {
+  const Elf_Note *Note = reinterpret_cast<const Elf_Note *>(Impl);
+  return Note->n_descsz;
+}
+
+const uint8_t *ElfLNote::getDesc() const {
+  const Elf_Note *Note = reinterpret_cast<const Elf_Note *>(Impl);
+  return reinterpret_cast<const uint8_t *>(Note) + sizeof(*Note) +
+      alignUp(getNameSize(), NoteAlignment);
+}
+
+uint64_t ElfLNote::getType() const {
+  const Elf_Note *Note = reinterpret_cast<const Elf_Note *>(Impl);
+  return Note->n_type;
+}
+
+#else // MAY_USE_LIBELF
+
+// Implementation based on LLVM ELF binary format.
+#include "llvm/Object/Binary.h"
+#include "llvm/Object/ELFObjectFile.h"
+#include "llvm/Object/ELFTypes.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Support/MemoryBuffer.h"
+
+using namespace llvm;
+using namespace llvm::ELF;
+using namespace llvm::object;
+
+class ElfLNoteImplBase {
+public:
+  virtual ~ElfLNoteImplBase() = default;
+  virtual ElfLNoteImplBase *clone() const = 0;
+  virtual size_t getNameSize() const = 0;
+  virtual const char *getName() const = 0;
+  virtual size_t getDescSize() const = 0;
+  virtual const uint8_t *getDesc() const = 0;
+  virtual uint32_t getType() const = 0;
+};
+
+template <class ELFT>
+class ElfLNoteImpl : public ElfLNoteImplBase {
+  using Elf_Note = typename ELFT::Note;
+  const Elf_Note Note;
+
+public:
+  ElfLNoteImpl(const Elf_Note Note) : Note(Note) {}
+  ElfLNoteImpl(const ElfLNoteImpl &) = default;
+  ElfLNoteImplBase *clone() const {
+    return new ElfLNoteImpl(*this);
+  }
+  ~ElfLNoteImpl() = default;
+  size_t getNameSize() const override {
+    return Note.getName().size();
+  }
+  const char *getName() const override {
+    return Note.getName().data();
+  }
+  size_t getDescSize() const override {
+    return Note.getDesc().size();
+  }
+  const uint8_t *getDesc() const override {
+    return Note.getDesc().data();
+  }
+  uint32_t getType() const override {
+    return Note.getType();
+  }
+};
+
+class ElfLNoteIteratorImplBase {
+protected:
+  const endianness TargetEndianness;
+  const bool Is64Bits;
+  const bool IsSectionIterator;
+
+  ElfLNoteIteratorImplBase(endianness TargetEndianness, bool Is64Bits, bool IsSectionIterator)
+    : TargetEndianness(TargetEndianness),
+      Is64Bits(Is64Bits),
+      IsSectionIterator(IsSectionIterator) {}
+
+public:
+  ElfLNoteIteratorImplBase(const ElfLNoteIteratorImplBase &) = default;
+  virtual ~ElfLNoteIteratorImplBase() = default;
+  virtual ElfLNoteIteratorImplBase *clone() const = 0;
+  virtual ElfLNoteIteratorImplBase &operator++() = 0;
+  virtual bool operator==(const ElfLNoteIteratorImplBase &) const = 0;
+  virtual ElfLNoteImplBase *operator*() const = 0;
+
+  endianness getEndianness() const {
+    return TargetEndianness;
+  }
+
+  bool is64Bits() const {
+    return Is64Bits;
+  }
+
+  bool isSectionIterator() const {
+    return IsSectionIterator;
+  }
+};
+
+template <class ELFT>
+class ElfLNoteIteratorImpl : public ElfLNoteIteratorImplBase {
+protected:
+  using NoteIterator = typename ELFT::NoteIterator;
+
+  const ELFFile<ELFT> &EF;
+  NoteIterator NotesIt;
+  Error &Err;
+
+  explicit ElfLNoteIteratorImpl(const ELFFile<ELFT> &EF, Error &Err, bool IsSectionIterator)
+    : ElfLNoteIteratorImplBase(ELFT::TargetEndianness, ELFT::Is64Bits, IsSectionIterator),
+      EF(EF), NotesIt(EF.notes_end()), Err(Err) {}
+
+public:
+  ElfLNoteIteratorImpl(const ElfLNoteIteratorImpl&) = default;
+  virtual ~ElfLNoteIteratorImpl() = default;
+
+  static bool classof(const ElfLNoteIteratorImplBase *B) {
+    return (B->getEndianness() == ELFT::TargetEndianness &&
+            B->is64Bits() == ELFT::Is64Bits);
+  }
+};
+
+template <class ELFT>
+class ElfLSectionNoteIteratorImpl : public ElfLNoteIteratorImpl<ELFT> {
+  using Elf_Shdr = typename ELFT::Shdr;
+  using Elf_Shdr_Range = typename ELFT::ShdrRange;
+  using NoteIterator = typename ElfLNoteIteratorImpl<ELFT>::NoteIterator;
+  using SectionsIteratorTy = typename Elf_Shdr_Range::iterator;
+
+  SectionsIteratorTy SectionsIt;
+
+  const ELFFile<ELFT> &getEF() const {
+    return this->EF;
+  }
+  const NoteIterator &getNotesIt() const {
+    return this->NotesIt;
+  }
+  Error &getErr() const {
+    return this->Err;
+  }
+  NoteIterator &getNotesIt() {
+    return this->NotesIt;
+  }
+  SectionsIteratorTy section_begin() const {
+    Expected<Elf_Shdr_Range> Sections = getEF().sections();
+    if (!Sections)
+      return SectionsIteratorTy();
+
+    return Sections->begin();
+  }
+
+  SectionsIteratorTy section_end() const {
+    Expected<Elf_Shdr_Range> Sections = getEF().sections();
+    if (!Sections)
+      return SectionsIteratorTy();
+
+    return Sections->end();
+  }
+
+  bool isEqual(const ElfLSectionNoteIteratorImpl &Lhs,
+               const ElfLSectionNoteIteratorImpl &Rhs) const {
+    // Check for end() iterators, first.
+    if (Lhs.SectionsIt ==  section_end() &&
+        Rhs.SectionsIt == section_end())
+      return true;
+
+    if (Lhs.SectionsIt != Rhs.SectionsIt)
+      return false;
+
+    return Lhs.getNotesIt() == Rhs.getNotesIt();
+  }
+
+  void autoAdvance(bool IsFirst = false) {
+    if (SectionsIt == section_end())
+      return;
+
+    if (getNotesIt() != getEF().notes_end())
+      return;
+
+    // SectionsIt is not an end iterator, and NotesIt is an end()
+    // iterator.
+    //
+    // If IsFirst is true, then we just in the initial state, and
+    // we need to set SectionsIt to the first SHT_NOTE section (if any),
+    // and, then, NotesIt to the first note in this section.
+    //
+    // If IsFirst is false, then we've reached the end of the current
+    // SHT_NOTE section, and should find the next section with notes.
+    if (!IsFirst || SectionsIt->sh_type != ELF::SHT_NOTE)
+      ++SectionsIt;
+
+    while (SectionsIt != section_end() &&
+           SectionsIt->sh_type != ELF::SHT_NOTE) {
+      ++SectionsIt;
+    }
+
+    if (SectionsIt == section_end()) {
+      // No more sections.
+      return;
+    }
+
+    const Elf_Shdr &Section = *SectionsIt;
+    getNotesIt() = getEF().notes_begin(Section, getErr());
+
+    // Auto advance the iterator, if the NOTE section
+    // does not contain any notes (e.g. some error happened
+    // during the note parsing).
+    autoAdvance();
+  }
+
+  bool operator!=(const ElfLSectionNoteIteratorImpl &Other) const {
+    return !(*this == Other);
+  }
+
+public:
+  ElfLSectionNoteIteratorImpl(const ELFFile<ELFT> &EF, Error &Err, bool IsEnd = false) 
+    : ElfLNoteIteratorImpl<ELFT>(EF, Err, true) {
+    if (IsEnd) {
+      SectionsIt = section_end();
+      // It is an end() iterator, if SectionsIt is an end() iterator.
+      return;
+    }
+
+    SectionsIt = section_begin();
+    autoAdvance(true);
+  }
+
+  ElfLSectionNoteIteratorImpl(const ElfLSectionNoteIteratorImpl &Copy) = default;
+
+  ElfLNoteIteratorImplBase *clone() const {
+    return new ElfLSectionNoteIteratorImpl(*this);
+  }
+
+  bool operator==(const ElfLNoteIteratorImplBase &Other) const override {
+    if (const ElfLSectionNoteIteratorImpl *OPtr = dyn_cast<const ElfLSectionNoteIteratorImpl>(&Other)) {
+      return isEqual(*this, *OPtr);
+    }
+    return false;
+  }
+
+  ElfLSectionNoteIteratorImpl &operator++() override {
+    assert(*this != ElfLSectionNoteIteratorImpl(getEF(), getErr(), true) &&
+           "Incrementing the end iterator.");
+    // Move the notes iterator within the current section.
+    ++getNotesIt();
+    autoAdvance();
+
+    return *this;
+  }
+
+  ElfLNoteImplBase *operator*() const override {
+    assert(*this != ElfLSectionNoteIteratorImpl(getEF(), getErr(), true) &&
+           "Dereferencing the end iterator.");
+    return new ElfLNoteImpl<ELFT>(*getNotesIt());
+  }
+
+  static bool classof(const ElfLNoteIteratorImplBase *B) {
+    return (ElfLNoteIteratorImpl<ELFT>::classof(B) &&
+            B->isSectionIterator() == true);
+  }
+};
+
+template <class ELFT>
+class ElfLSegmentNoteIteratorImpl : public ElfLNoteIteratorImpl<ELFT> {
+  using Elf_Phdr = typename ELFT::Phdr;
+  using Elf_Phdr_Range = typename ELFT::PhdrRange;
+  using NoteIterator = typename ElfLNoteIteratorImpl<ELFT>::NoteIterator;
+  using SegmentIteratorTy = typename Elf_Phdr_Range::iterator;
+
+  SegmentIteratorTy SegmentsIt;
+
+  const ELFFile<ELFT> &getEF() const {
+    return this->EF;
+  }
+  const NoteIterator &getNotesIt() const {
+    return this->NotesIt;
+  }
+  Error &getErr() const {
+    return this->Err;
+  }
+  NoteIterator &getNotesIt() {
+    return this->NotesIt;
+  }
+  SegmentIteratorTy segment_begin() const {
+    Expected<Elf_Phdr_Range> Segments = getEF().program_headers();
+    if (!Segments)
+      return SegmentIteratorTy();
+
+    return Segments->begin();
+  }
+
+  SegmentIteratorTy segment_end() const {
+    Expected<Elf_Phdr_Range> Segments = getEF().program_headers();
+    if (!Segments)
+      return SegmentIteratorTy();
+
+    return Segments->end();
+  }
+
+  bool isEqual(const ElfLSegmentNoteIteratorImpl &Lhs,
+               const ElfLSegmentNoteIteratorImpl &Rhs) const {
+    // Check for end() iterators, first.
+    if (Lhs.SegmentsIt == segment_end() &&
+        Rhs.SegmentsIt == segment_end())
+      return true;
+
+    if (Lhs.SegmentsIt != Rhs.SegmentsIt)
+      return false;
+
+    return Lhs.getNotesIt() == Rhs.getNotesIt();
+  }
+
+  void autoAdvance(bool IsFirst = false) {
+    if (SegmentsIt == segment_end())
+      return;
+
+    if (getNotesIt() != getEF().notes_end())
+      return;
+
+    // SegmentsIt is not an end iterator, and NotesIt is an end()
+    // iterator.
+    //
+    // If IsFirst is true, then we just in the initial state, and
+    // we need to set SegmentsIt to the first PT_NOTE segment (if any),
+    // and, then, NotesIt to the first note in this segment.
+    //
+    // If IsFirst is false, then we've reached the end of the current
+    // PT_NOTE segment, and should find the next segment with notes.
+    if (!IsFirst || SegmentsIt->p_type != ELF::SHT_NOTE)
+      ++SegmentsIt;
+
+    while (SegmentsIt != segment_end() &&
+           SegmentsIt->p_type != ELF::PT_NOTE) {
+      ++SegmentsIt;
+    }
+
+    if (SegmentsIt == segment_end()) {
+      // No more segments.
+      return;
+    }
+
+    const Elf_Phdr &Segment = *SegmentsIt;
+    getNotesIt() = getEF().notes_begin(Segment, getErr());
+
+    // Auto advance the iterator, if the NOTE segment
+    // does not contain any notes (e.g. some error happened
+    // during the note parsing).
+    autoAdvance();
+  }
+
+  bool operator!=(const ElfLSegmentNoteIteratorImpl &Other) const {
+    return !(*this == Other);
+  }
+
+public:
+  ElfLSegmentNoteIteratorImpl(const ELFFile<ELFT> &EF, Error &Err, bool IsEnd = false) 
+    : ElfLNoteIteratorImpl<ELFT>(EF, Err, false) {
+    if (IsEnd) {
+      SegmentsIt = segment_end();
+      // It is an end() iterator, if SegmentsIt is an end() iterator.
+      return;
+    }
+
+    SegmentsIt = segment_begin();
+    autoAdvance(true);
+  }
+
+  ElfLSegmentNoteIteratorImpl(const ElfLSegmentNoteIteratorImpl &Copy) = default;
+
+  ElfLNoteIteratorImplBase *clone() const {
+    return new ElfLSegmentNoteIteratorImpl(*this);
+  }
+
+  bool operator==(const ElfLNoteIteratorImplBase &Other) const override {
+    if (const ElfLSegmentNoteIteratorImpl *OPtr = dyn_cast<const ElfLSegmentNoteIteratorImpl>(&Other)) {
+      return isEqual(*this, *OPtr);
+    }
+    return false;
+  }
+
+  ElfLSegmentNoteIteratorImpl &operator++() override {
+    assert(*this != ElfLSegmentNoteIteratorImpl(getEF(), getErr(), true) &&
+           "Incrementing the end iterator.");
+    // Move the notes iterator within the current segment.
+    ++getNotesIt();
+    autoAdvance();
+
+    return *this;
+  }
+
+  ElfLNoteImplBase *operator*() const override {
+    assert(*this != ElfLSegmentNoteIteratorImpl(getEF(), getErr(), true) &&
+           "Dereferencing the end iterator.");
+    return new ElfLNoteImpl<ELFT>(*getNotesIt());
+  }
+
+  static bool classof(const ElfLNoteIteratorImplBase *B) {
+    return (ElfLNoteIteratorImpl<ELFT>::classof(B) &&
+            B->isSectionIterator() == false);
+  }
+ 
+};
+
+class ElfLImplBase {
+public:
+  ElfLImplBase() = default;
+  ElfLImplBase(const ElfLImplBase &) = delete;
+  ElfLImplBase &operator=(const ElfLImplBase &) = delete;
+  virtual ~ElfLImplBase() = default;
+  virtual uint16_t getEMachine() const = 0;
+  virtual uint16_t getEType() const = 0;
+
+  virtual ElfLNoteIteratorImplBase *create_section_note_iterator_impl(bool IsEnd) const = 0;
+  virtual ElfLNoteIteratorImplBase *create_segment_note_iterator_impl(bool IsEnd) const = 0;
+};
+
+template <class ELFT>
+class ElfLImpl : public ElfLImplBase {
+  std::unique_ptr<ELFObjectFile<ELFT>> File;
+  Error *Err = nullptr;
+
+  friend class ElfL;
+
+public:
+  ElfLImpl(std::unique_ptr<ObjectFile> F) {
+    ObjectFile *FPtr = F.release();
+    if (auto *Obj = dyn_cast<ELFObjectFile<ELFT>>(FPtr))
+      File = std::unique_ptr<ELFObjectFile<ELFT>>(Obj);
+    else
+      assert("Not an ELF object file, or ELF class is wrong.");
+
+    Err = new Error(std::move(Error::success()));
+  }
+  ElfLImpl(const ElfLImpl &) = delete;
+  ElfLImpl &operator=(const ElfLImpl &) = delete;
+  virtual ~ElfLImpl() {
+    if (!Err)
+      return;
+
+    if (*Err) {
+      auto ErrorString = toString(std::move(*Err));
+      DP("Destroying ELF object parsed with errors: %s\n",
+         ErrorString.c_str());
+    } else {
+      delete Err;
+    }
+    Err = nullptr;
+  }
+  uint16_t getEMachine() const override {
+    return cast<ELFObjectFileBase>(File.get())->getEMachine();
+  }
+  uint16_t getEType() const override {
+    return cast<ELFObjectFileBase>(File.get())->getEType();
+  }
+
+  ElfLNoteIteratorImplBase *create_section_note_iterator_impl(
+      bool IsEnd) const override {
+    return new ElfLSectionNoteIteratorImpl<ELFT>(File->getELFFile(), *Err, IsEnd);
+  }
+
+  ElfLNoteIteratorImplBase *create_segment_note_iterator_impl(
+      bool IsEnd) const override {
+    return new ElfLSegmentNoteIteratorImpl<ELFT>(File->getELFFile(), *Err, IsEnd);
+  }
+};
+
+ElfL::ElfL(char *Begin, size_t Size) {
+  StringRef StrBuf(Begin, Size);
+  std::unique_ptr<MemoryBuffer> MemBuf =
+      MemoryBuffer::getMemBuffer(StrBuf, "", false);
+  Expected<std::unique_ptr<ObjectFile>> BinOrErr =
+      ObjectFile::createELFObjectFile(MemBuf->getMemBufferRef(),
+                                      /*InitContent=*/false);
+  if (!BinOrErr)
+    return;
+
+  if (isa<ELF64LEObjectFile>(BinOrErr->get())) {
+    Impl = reinterpret_cast<void *>(new ElfLImpl<ELF64LE>(std::move(*BinOrErr)));
+  } else if (isa<ELF32LEObjectFile>(BinOrErr->get()))
+    Impl = reinterpret_cast<void *>(new ElfLImpl<ELF32LE>(std::move(*BinOrErr)));
+  else if (isa<ELF32BEObjectFile>(BinOrErr->get()))
+    Impl = reinterpret_cast<void *>(new ElfLImpl<ELF32BE>(std::move(*BinOrErr)));
+  else if (isa<ELF64BEObjectFile>(BinOrErr->get()))
+    Impl = reinterpret_cast<void *>(new ElfLImpl<ELF64BE>(std::move(*BinOrErr)));
+}
+
+ElfL::~ElfL() {
+  ElfLImplBase *EImpl = reinterpret_cast<ElfLImplBase *>(Impl);
+  delete EImpl;
+}
+
+bool ElfL::isValidElf() const {
+  return Impl;
+}
+
+const char *ElfL::getErrmsg(int N) const {
+  return "LLVM ELF error";
+}
+
+uint16_t ElfL::getEMachine() const {
+  assert(isValidElf() && "Invalid ELF.");
+  ElfLImplBase *EImpl = reinterpret_cast<ElfLImplBase *>(Impl);
+  return EImpl->getEMachine();
+}
+
+uint16_t ElfL::getEType() const {
+  assert(isValidElf() && "Invalid ELF.");
+  ElfLImplBase *EImpl = reinterpret_cast<ElfLImplBase *>(Impl);
+  return EImpl->getEType();
+}
+
+bool ElfL::isDynType(uint16_t Ty) {
+  return Ty == ET_DYN;
+}
+
+ElfLSectionNoteIterator::ElfLSectionNoteIterator(const void *I, bool IsEnd) {
+  const ElfLImplBase *EImpl = reinterpret_cast<const ElfLImplBase *>(I);
+  // Create new ElfLSectionNoteIteratorImpl<ELFT> object.
+  Impl = EImpl->create_section_note_iterator_impl(IsEnd);
+}
+
+ElfLSectionNoteIterator::~ElfLSectionNoteIterator() {
+  const ElfLNoteIteratorImplBase *IImpl =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Impl);
+  delete IImpl;
+}
+
+ElfLSectionNoteIterator::ElfLSectionNoteIterator(const ElfLSectionNoteIterator &Other) {
+  const ElfLNoteIteratorImplBase *IImpl =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Other.Impl);
+  Impl = IImpl->clone();
+}
+
+bool ElfLSectionNoteIterator::operator==(const ElfLSectionNoteIterator Other) const {
+  const ElfLNoteIteratorImplBase *Lhs =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Impl);
+  const ElfLNoteIteratorImplBase *Rhs =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Other.Impl);
+  return (*Lhs == *Rhs);
+}
+
+bool ElfLSectionNoteIterator::operator!=(const ElfLSectionNoteIterator Other) const {
+  return !(*this == Other);
+}
+
+ElfLSectionNoteIterator &ElfLSectionNoteIterator::operator++() {
+  ElfLNoteIteratorImplBase *EImpl =
+      reinterpret_cast<ElfLNoteIteratorImplBase *>(Impl);
+  ++(*EImpl);
+  return *this;
+}
+
+ElfLNote ElfLSectionNoteIterator::operator*() const {
+  return ElfLNote(Impl);
+}
+
+ElfLSectionNoteIterator ElfL::section_notes_begin() const {
+  assert(isValidElf() && "Invalid ELF.");
+  return ElfLSectionNoteIterator(reinterpret_cast<const ElfLImplBase *>(Impl));
+}
+
+ElfLSectionNoteIterator ElfL::section_notes_end() const {
+  assert(isValidElf() && "Invalid ELF.");
+  return ElfLSectionNoteIterator(reinterpret_cast<const ElfLImplBase *>(Impl), true);
+}
+
+ElfLSegmentNoteIterator::ElfLSegmentNoteIterator(const void *I, bool IsEnd) {
+  const ElfLImplBase *EImpl = reinterpret_cast<const ElfLImplBase *>(I);
+  // Create new ElfLSegmentNoteIteratorImpl<ELFT> object.
+  Impl = EImpl->create_segment_note_iterator_impl(IsEnd);
+}
+
+ElfLSegmentNoteIterator::~ElfLSegmentNoteIterator() {
+  const ElfLNoteIteratorImplBase *IImpl =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Impl);
+  delete IImpl;
+}
+
+ElfLSegmentNoteIterator::ElfLSegmentNoteIterator(const ElfLSegmentNoteIterator &Other) {
+  const ElfLNoteIteratorImplBase *IImpl =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Other.Impl);
+  Impl = IImpl->clone();
+}
+
+bool ElfLSegmentNoteIterator::operator==(const ElfLSegmentNoteIterator Other) const {
+  const ElfLNoteIteratorImplBase *Lhs =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Impl);
+  const ElfLNoteIteratorImplBase *Rhs =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Other.Impl);
+  return (*Lhs == *Rhs);
+}
+
+bool ElfLSegmentNoteIterator::operator!=(const ElfLSegmentNoteIterator Other) const {
+  return !(*this == Other);
+}
+
+ElfLSegmentNoteIterator &ElfLSegmentNoteIterator::operator++() {
+  ElfLNoteIteratorImplBase *EImpl =
+      reinterpret_cast<ElfLNoteIteratorImplBase *>(Impl);
+  ++(*EImpl);
+  return *this;
+}
+
+ElfLNote ElfLSegmentNoteIterator::operator*() const {
+  return ElfLNote(Impl);
+}
+
+ElfLSegmentNoteIterator ElfL::segment_notes_begin() const {
+  assert(isValidElf() && "Invalid ELF.");
+  return ElfLSegmentNoteIterator(reinterpret_cast<const ElfLImplBase *>(Impl));
+}
+
+ElfLSegmentNoteIterator ElfL::segment_notes_end() const {
+  assert(isValidElf() && "Invalid ELF.");
+  return ElfLSegmentNoteIterator(reinterpret_cast<const ElfLImplBase *>(Impl), true);
+}
+
+ElfLNote::ElfLNote(const void *IteratorImpl) {
+  const ElfLNoteIteratorImplBase *IImpl =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(IteratorImpl);
+  Impl = **IImpl;
+}
+
+ElfLNote::ElfLNote(const ElfLNote &Other) {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  Impl = NImpl->clone();
+}
+
+ElfLNote::~ElfLNote() {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  delete NImpl;
+}
+
+uint64_t ElfLNote::getNameSize() const {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  return NImpl->getNameSize();
+}
+
+const char *ElfLNote::getName() const {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  return NImpl->getName();
+}
+
+uint64_t ElfLNote::getDescSize() const {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  return NImpl->getDescSize();
+}
+
+const uint8_t *ElfLNote::getDesc() const {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  return NImpl->getDesc();
+}
+
+uint64_t ElfLNote::getType() const {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  return NImpl->getType();
+}
+#endif // MAY_USE_LIBELF

openmp/libomptarget/plugins/remote/server/CMakeLists.txt

 ##===----------------------------------------------------------------------===##
 #
 # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #
 ##===----------------------------------------------------------------------===##
 #
 # Build server for remote offloading.
 #
 ##===----------------------------------------------------------------------===##
 
-include_directories(${LIBOMPTARGET_DEP_LIBELF_INCLUDE_DIRS})
 include_directories(${LIBOMPTARGET_SRC_DIR})
 include_directories(${LIBOMPTARGET_INCLUDE_DIR})
 include_directories(${GRPC_INCLUDE_DIR})
 include_directories(${RPC_INCLUDE_DIR})
 
 add_executable(openmp-offloading-server
         ${LIBOMPTARGET_SRC_FILES}
         ${GRPC_SRC_FILES}
         ${RPC_SRC_DIR}/Utils.cpp
         Server.cpp
         OffloadingServer.cpp
 )
 
 target_link_libraries(openmp-offloading-server
         grpc++
         protobuf
         ${OPENMP_PTHREAD_LIB}
-        "-ldl" "-lomp" "-fopenmp" "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../../exports" ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES})
+        "-ldl" "-lomp" "-fopenmp" "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../../exports")